The original title of the film was Bad Food, and was to be about food attacking people. Eventually, this idea was scrapped, due to lack of extras and lack of progress with the script. The idea was changed entirely, but the characters were kept in and were still the same.
Joseph Collins is a big fan of rock and metal, especially the obscure stuff, so he used a bunch of songs from unsigned bands to avoid any copyright and to give a little free promotion.
Joseph Collins intentionally shot and cut multiple scenes and endings, saying that they were for the international versions. This is a play on Game of Death, as the Cantonese and Mandarin versions included additional scenes and had different endings than the US version.